1. Field of the Invention
The present invention relates to a method for analyzing and evaluating the quality of a light source, and more particularly to a light source quality evaluating method by using spectral resemblance with respect to the blackbody radiation.
2. Description of the Prior Art
Light is an important find and use in human civilization society; therefore, according to natural light emitted by sun, the ancient people are able to rise with the sunrise and take rest with the sunset. With the advancement of the technologies, the artificial light is developed from bulb to incandescent bulb after the Edison invents the bulb. Moreover, the solid-state lighting (SSL), such as light-emitting diode (LED), organic light-emitting diode (OLED) and polymer light-emitting diode (PLED), the latest lighting technology is further be proposed.
ELI (ergonomic lighting indicator) is a comprehensive evaluating standard for lighting quality. Please refer to FIG. 1, there is shown a degree indicator diagram of the ELI. As shown in FIG. 1, ELI includes 5 indicating indices for evaluating a light source, the indicating indices consists of:    (A) visual performance, including the factors of illumination, color rendering, and contrast;    (B) vista, including the factors of user psychology, visual hierarchy, and building materials;    (C) visual comfort, including the factors of light distribution uniformity, the existence of uncomfortable glare, and light flashes;    (D) vitality, including the factors of impacts on people's psychological and stimulation; and    (E) empowerment, including the factors of individual light modulation, selective lighting scenes and layouts.
Therefore, through above descriptions, it is able to know there have 4 indicating indices of the ELI being correspondent with the physiological perception of human, which are visual performance, vista, vitality, and empowerment. Accordingly, it is able to further understand that the human's physiological perception is very important for the ELI.
However, differing from the ELI, CRI (color rendering index) is used for evaluating the light quality by distinct way. The method for measuring the CRI of a light source includes the steps of: Firstly, making a light source to illuminate an object for facilitating the object reveals its object color; next, making a reference light source to illuminate the object for facilitating the object reveals a reference object color. Eventually, quantitatively comparing the object color with the reference object color according to 8 color samples of DIN 6169, therefore the CRI of the light source can be obtained.
Through the method steps for measuring the CRI of the light source, it is able to know that the primary step is comparing the object color with the reference object color according to 8 color samples of DIN 6169; obviously, the CRI—measuring steps does not concern or refer human's physiological perception. Based on this reason, predictably, the light source having high CRI value may not show good ELI values on visual performance, vista, vitality, and empowerment. It means that CRI may not be the best index for light source quality because of lacking fairness and consistency.
Accordingly, in view of the CRI may not be the best index for light source quality, the inventor of the present application has made great efforts to make inventive research thereon and eventually provided a light quality evaluating device by using spectral resemblance with respect to the blackbody radiation.